Posted
by
timothy
on Thursday June 21, 2012 @02:47PM
from the introducing-the-samsung-cavitate dept.

An anonymous reader writes "For decades, researchers have been trying to build boats, submarines, and torpedoes that make use of supercavitation — a bubble layer around the hull that drastically reduces friction and enables super-fast travel. Now a company in New Hampshire called Juliet Marine Systems has built and tested such a craft, and says it is the world's fastest underwater vehicle. The ship, called the 'Ghost,' looks like two supercavitating torpedoes with a command module on top, and can carry 18 people plus weapons and supplies. The company is in talks with the U.S. Navy to build a version of the ship that can guard the fleet against swarm attacks by small boats. The question is how well it really works, and whether it can be used reliably and effectively on the high seas."

I thought in the submariners' world cavitation was a bad thing? Reason: It makes a lot of noise. That's why they move around slowly at 10-15 knots, rather than full speed with the propeller producing noisy bubbles. (And also why the Russians kept trying to steal our propeller tech, because their propellers tended to cavitate, making them easy targets.)

There's a difference between cavitation and supercavitation. Supercavitation takes those noisy bubbles that are destroying your propeller and extends them to enclose the entire vessel. This reduces the amount of surface in contact with the water, which greatly reduces drag, and all of a sudden you're rocketing along at 200 miles per hour and don't particularly care if people hear you coming.

You are either confused or you didn't read TFA. This is a $10 million private sector development. Yes they are trying to interest the Navy/CG but were they really interested is would have been mentioned. If you want to beat on government spending go find a subject where the government is actually doing the spending.

You don't really care if you can be heard by sonar if you're doing 100 knots submerged. Torpedoes can't hit you except by dumb luck straight on.

Of course this thing is not completely submerged so you do have a chance against it with guns. Possibly also with a missile, but with no heat signature (it probably dumps waste heat in the water) and low radar signature you will have to get quite lucky.

Basically, scientists say the "supercavitating boat" is basically a bunch of BS and/or not that likely. Hype as usual.

Which scientists? Supercavitating torpedoes go back to the 1970s Shkval [wikipedia.org] for Russian models and the more recent Barracuda [wikipedia.org] for the Germans. Making a catamaran above a pair of them does not seem implausible.

Boat. not Torpedo. Carrying a pair of torpedos in the water with supercavitating propellers on the front does not mean the boats supercavitate. Claiming a catamaran can go through the water would require more than just the "torpedos" to supercavitate. RTFA. A catamaran above the water is substantially different than the claims at hand - which is *underwater*.

I didn't say a thing about torpedos, because that's not even a question here.

Also to say they can't be detected by sonar is wrong - they can't be detected by sonar from behind or directly in front, since the boat would be moving faster than the sonar waves straight on going forward (unless the boat also absorbs sonar, that is).

Also to say they can't be detected by sonar is wrong - they can't be detected by sonar from behind or directly in front, since the boat would be moving faster than the sonar waves straight on going forward (unless the boat also absorbs sonar, that is).

For your claim to be true, it would have to be moving around 3300 mph. Not likely. Cavitation generates a huge amount of noise. For a "supercavitating" torpedo you don't care because the target can't outrun it or often react fast enough to make evasive maneuvers.

It would also be nice if the article made the distinction between cavitating and injecting air at the bow. Air injection at the bow has some beneficial benefit for drag (not called friction in water) and acoustic (isolates hull noise from the wat

Great, another public relations company "news". No reporter was involved on this, 100% paid advertisment.This is journalism today. You want to be on the news, just pay for it. Even slashdot is part of the system now.BTW this work for universities too, that's why MIT makes the new every time they wire a microcontroller to a dishwasher.

1st: Radar cannot penetrate underwater and the part of the GHOST ships that are above water have the same type of design and material as the stealth fighter.2nd: One of the goals of supercavitation is to achieve faster-than-sound speed underwater. Since sonar uses sound waves to detect objects, if you could travel toward a ship equipped with sonar you could reach them before they had a chance to detect you. Other ships would eventually detect you, but there would be such lag in detection that it would b

yep... ~1500m/s which is around mach 4.5. 2000kph faster than the SR-71, which is the fastest air breathing manned aircraft ever built. 2000kph slower than the fastest rocket powered manned aircraft, none of which can achieve anywhere near those speeds at low altitude.

yes, that's crazy fast... speed of sound in water is 3,319.2 MPH, almost a mile per second. The SR-71 isn't quite that fast, though the X-15 is, [wikipedia.org] but if the X-15 counts as a plane... why not count the Space Shuttle: can do Mach 20 or as fast as we want to make it go in space...

According to the article (ahem) the top speed has not been announced but is expected to be around 100 MPH, which is of course slower than conventional speedboats. Moreover it is doubtful it could maneuver near this top speed. All this is in the article. I don't see how this could possibly be stealthy to sonobouys etc.

The article claims it is much smoother than a hydroplane in rough seas. Of course, since it is a hydrofoil. That doesn't mean it's smoother than other hydrofoil craft.

The US Navy had a program to integrate the CIWS gun with the Oto Melara 76mm Compact 75 on US frigates. The project, called Swarmbuster, does not seem to have been completed. The Compact 75 is a long range 3 inch gun that is effective in the counter-ship counter-boat role. It also has ammunition with sufficient burst to blow a swarming boat out of the water. Improved versions of the Oto gun fire 100 rounds per minute or better. It can use the same sensor as the CIWS gun.

So a couple years ago I was recollecting to a friend who is in the U.S. Coast Guard about a science program I had seen on TV about a new boat the CG was experimenting with which used hydrofoils to lift the main hull clear of the water when the boat was at speed. I asked him whatever happened to that program as it looked super interesting and promising for high speed water craft. He said they were abandoned because they would routinely be cruising along and strike a submerged log floating in the water which would rip one or more of the hydro foil skis off, and that would be the end of that boat. It happened *all* the time.

This vehicle appears to me that it would suffer the same problem - strike something submerged just below the surface and one of those pontoons becomes damaged or separated and down goes your boat.

A regular boat hull has the advantage of coming up to an obstacle at speed like that and skip right over the top of it, no harm, no foul, (albeit with a horrible sound within). At least the CG ships had a regular hull + the hydrofoil skis so that if there was a problem of that sort, it just sank back down to the regular hull. For the design proposed, it doesn't look like the craft would even float without the two pontoons, so those guys would be farkt. I suggest not buying it.

So a couple years ago I was recollecting to a friend who is in the U.S. Coast Guard about a science program I had seen on TV about a new boat the CG was experimenting with which used hydrofoils to lift the main hull clear of the water when the boat was at speed. I asked him whatever happened to that program as it looked super interesting and promising for high speed water craft. He said they were abandoned because they would routinely be cruising along and strike a submerged log floating in the water which would rip one or more of the hydro foil skis off, and that would be the end of that boat. It happened *all* the time.

The Navy had a bigger hydrofoil project - the Pegasus class [wikipedia.org], built by Boeing. Hitting a submerged log is a euphemism. The story I heard (from some of the guys who helped design and test it for the Navy) was that they were averaging one whale strike a year per ship.

Boeing even took that into consideration with its design. The foils need to rotate up anyway for slow-speed operation in shallow harbors. So on the front foil, they added what they called a structural fuse. Like an electrical fuse is designed to burn out before the wiring does, they added a big metal bar to the linkage holding the foils in place. The bar was designed to break before the foil or its mounting points on the hull if the foil struck anything (a whale or a log). Once the bar broke, the foil would be free to collapse upward. The ship wouldn't be very operational afterwards and would suffer minor damage, but at least it wouldn't sink and an expensive foil wouldn't be ripped off. From what I was told, it worked pretty well. But the frequency of whale strikes*, and the downtime associated with recovering and repairing the ship after one, was just too much and they canceled the program.

Boeing adapted most of the technology into a passenger hydrofoil [wikipedia.org] which I believe is still in service in a few areas around the world. They eventually sold the design and rights to Kawasaki Heavy Industries. I got to ride one when I visited Japan, and it feels more like flying in a plane that it does riding a ship. There's a slight rocking motion, but it's very muted compared to a regular monohull or catamaran. The hull is above the waves and swells, so the ship is mostly unaffected by them.

* The foils are basically wings "flying" underwater and are bound by much of the same physics as aircraft wings. If you go too slowly, they stall and the ship sinks bank into the water. A twist though is that you can get cavitation along the top of the foil. In the air, a wing creates a low pressure zone on top, causing the air underneath to lift the plane. In the water, this low pressure zone can drop so much in pressure that the water boils into vapor and cavitates. Once it cavitates, the water flow is disrupted and the foil loses its lift. (Same problem that propellers suffer, unless they're designed to supercavitate - generate thrust despite cavitating.)

However, since water increases in pressure rapidly with depth, this can be solved by simply running the foils at a deeper depth. Beyond a certain depth, the ambient water pressure is enough to prevent cavitation. This does mean though that you cannot simply "fly" the ship along the top of the water thus minimizing the danger from whale strikes. The minimum depth of the foils will be determined by their geometry and the weight of the ship. So the foils are usually running several meters underwater, making a whale strike a catastrophic event.

The fact that the boat exists indicates that the torpedo technology is probably already on board US vessels - meaning that the US could sink just about any ship before the enemy even knew torpedoes where in the water.

I doubt it, otherwise the capability would have been demonstrated. It is hardly a new technology, the USSR having it in the early 70s and Iran demonstrating their version about a decade ago. A German company has their own version too.

There are plenty of other weapons the US doesn't have. Russia and India have jointly developed supersonic cruise missiles that fly at speeds far in excess of anything the US has. It isn't a cock measuring competition, try not to develop a complex about it.

I think we already have the perfect attack plane for this mission, the A-10 [wikipedia.org]. It can easily keep up, was designed to visually target, and would obliterate a boat like this in a few shells.

The Russians have had supercavitating torpedoes [wikipedia.org] operational and in use since 1977, but they only reach 370 km/h [wikipedia.org]. For comparison, the speed of sound in seawater is roughly 1.5 km/s [dosits.org], so roughly 14.6x faster. The US Navy developed their own, but decided to stick with what they already had for a variety of reasons. To say the least, those speeds are nowhere close to hitting the target before they realize it's coming.

Also, detection is trivial with supercavitation, since the propulsion necessary to sustain it i

Supercavitating is super noisy and very detectable by underwater ears.The supercavitating transition layer reflects sound very well = also detectable.at 300 to 500 miles per hour the immediacy compensates for the noise which makes it hard to localize, but you sure know it was around.

This is like a supercavitating hydrofoil. This is not like a WiG (Wing in Ground) craft. Similar to a cement mixer full of bowling balls falling off a cliff, it is loud and fast (and I assume can be dangerous, too). It is not like a ham sandwich. It's not a big truck. It's not something you just dump something on.

Frankly, the nuclear powered rail gun is probably going to be the biggest improvement in a long time. The navy will develop it for their new magnetic rail launch system for jets off a carrier, then move it to direct attack..

This type of boat is probably too limited in usefulness to be adopted by the navy. In terms of R&D capabilities it feels a lot like the experiments from the 1960s to develop militarized hydrofoils - the Canadian HMCS Bras d'Or [wikipedia.org] being one good example. Despite impressive stability and speeds in excess of 60 knots (70mph), the limited load capacity and range made the prototypes unsuitable for military use.

The biggest hit, however, was the introduction of missiles. The difference between 20 and 30 knots isn't all that important when you're defending against a Sea Sparrow running at 500 mph. In WWII there were lots of destroyers running in excess of 35 knots. Now it's just the nuke-powered ACs that do top speeds, and everyone else is more worried about conserving fuel.

That means the proposed boat is really just a replacement for patrol vessels or stealth assault craft, and it doesn't look like the advantages of the design outweigh the compromises in handling, noise, carrying capacity and cost.

It's limited in usefulness if you were looking to deploy them in the traditional sense of leaving port and not returning to land for months. However, you could put them on a carrier like we do aircraft, and launch them from there for regular patrols, assaults, and as a way to quickly gain superiority in the water in naval battles.

You'd just need to retrofit some your smaller escort ships to each be able to launch one or two. Or build a whole new class of carriers for them, which while cool, probably isn't e

Its also not clear to me that it would fill a different niche than an ekranoplan (ground effect flying boat). These were developed by the Russians and worked, but as far as I know were not found to be militarily useful.

This article makes no sense."The angle of the struts that connect the foils to the command module is adjustable&mdash;so the craft can ride high in choppy seas and at high speeds (so waves don&rsquo;t hit the middle part), and low in calm water and at lower speeds.

&ldquo;We&rsquo;re basically riding on two supercavitating torpedoes. And we&rsquo;ve put a boat on top of it,&rdquo; Sancoff says."

It sounds like they use an envelope of bubbles to encase the nacelles in air to reduce the friction between the nacelles and the water. If it works for increasing the speed through water, maybe the same methodology can be applied to increase speed of travel through air.... Surround the craft with a vacuum to reduce air friction. Maybe call it superturbulence.

I did a little research on some of the claims in the article;From the article;

It was there, in 2000, that he first got inspiration for Juliet Marine and the Ghost ship. Sancoff was sitting in a conference room when he heard the U.S.S. Cole had been attacked off the coast of Yemen by a small boat loaded with explosives.

The USS Cole was attacked while in port tied up along a jetty refueling. All of it's radars and weapons systems were down and the ship was defenseless. An innocent looking small boat moved up to the hull and exploded. That was a port security failure and nothing to do with the weapons capability of the Cole. Referring to that incident in the context of massed small boat attacks is bunk.

From the article;

I looked at the Fleet Battle Experiment Juliet Final Summary Report [dtic.mil] and nowhere did it mention a high number of losses due to small boat attacks. Even if the statement is true, Juliet took place 9 years ago and I bet there has been a lot of learning and experimentation since then.

Now lets look at the technology. In general it works by a propeller spinning so fast it creates enough low pressure behind the propeller to boil the water and create water vapour which reduces drag along the rest of the sponson. Here are a few issues;1. The way a propeller works is that it pulls in water that is approaching the propeller at one velocity and ejects it at a higher velocity from the back of the propeller. This creates a low pressure area behind the propeller. If the velocity differential is enough the low pressure is enough to lower the boiling point of the water and cause it to turn to water vapour. This large velocity differential in generally obtained when a vessel is accelerating or decelerating. There is a point at which the velocity of the ship approaches the maximum velocity of the water ejected from the propeller. This will decrease the low pressure to a point at which cavitation will stop.2. Propeller cavitation is very hard equipment. I know the chief engineer on a ferry and he cringes every time he feels cavitation. He knows that they just spent thousands of dollars on propellers, bearings and shafts just because some sod at the helm didn't slow down at the right time. Anyone who has traveled on a ferry has experienced cavitation. It usually occurs during docking and the whole ship shakes. When propellers cavitate is is not a smooth process. Bubbles of water form on the back of the propeller, detach and then water slams back in. This causes damage to the propeller [wikipedia.org]. How long can the new ship go before expensive overhauls? Drag racers are rebuilt after every run, is it really feasible to use that same model on a warship? It may work on torpedoes but they are one use weapons.

The article makes several references like "to reach very high speeds at relatively low fuel cost." The question is relative to what? A conventional boat attempting 100 knots or a 30kt destroyer. If comparing with a high speed boat they may be less but pound for pound it is a lot more than a DDG. If the range of one of these vessels is only a few hundred mile it will be difficult to get in theater and spend much of it's time sitting next to a ship refueling.

I love the following statement;

Its fuel efficiency means it has greater range and can run longer missions than conventional boats and helicopters.

There is always an issue when using relative terms; in general they are meaningless.Technically speaking a 1% increase in range is longer. What is the actual difference in range and is it enough to self deploy? The military does not expect a helicopter to self deploy, hence the need for helicopter carriers [wikipedia.org] but it does expect its ships to self deploy. Sure the navy could use a cargo vessel to carry the new s

Supercavitationistic Bubblicious Warships,The enemy don't have this stuff, It's only found on our ships,Faster than the Russian navy, Chinese or Qatar ships,Supercavitationistic Bubblicious Warships.

Um diddle diddle diddle um diddle aye,

It goes a hundred knots per hour and uses little fuel,Looks just like the Bird of Prey from Star Trek #2,The DoD they can't believe the small size of the bill,The sucker was developed for just $150 mil....

Calling a sub a "boat" is actually the standard way of referring to a sub in the Navy. It's not an affectionate term, it's a standard one. If you called a sub a ship while you were in the Navy, you'd get corrected immediately.

Now, whether you thought that was proper for subs outside the Navy, I don't know. However, since this is being shopped to the Navy, it seems like a perfectly reasonable thing to call it.

Technically, a ship was a surface water craft (a boat) that had three masts and a bowsprit. Everything else had other names. When large boats no longer had masts or bowsprits the definition changed. Subs have just always been boats, no matter how large.

1) As far as I can tell, the command module never submerges. Could be wrong on that bit though.2) The inventor also calls it an airplane. " “It’s almost as much an aircraft as it is a boat,” says its inventor, Gregory Sancoff, the founder and CEO of Juliet Marine Systems, a private company in Portsmouth, NH."3) The article says it "looks like something out of Star Trek" and links to a bad image of a Romulan Bird of Pray. The drydock picture next to the link looks a lot more like a TNG/DS9/

The main compartment of the Ghost vessel, which houses the cockpit and controls, sits above the water in between two torpedo-shaped pontoons or “foils,” which are submerged and create all the buoyancy and propulsion for the craft.

Would be interesting to see it in the open ocean with the high waves. If the wave height is higher than the boat clearance it's similar to hitting the water surface at 100 mph. A nosedive at such a speed means the cockpit becomes a 12-seat grave.

The Ghost shown on the Juliet Marine web site (http://julietmarine.com/ [julietmarine.com]) is a surface ship that doesn't look anything like two torpedoes. In fact, if anything, it looks similar to an original Start Trek series shuttle craft with bigger (and fold-able) wings. Also Ghost was announces in Aug 2011, so where's the news exactly?

Ouch. That article was so full of buzzwords and hype that my brain started cavitating.

Here [xconomy.com] is a diagram from the patent application that shows the entire vehicle. It definitely looks like a shuttle craft, but the "two torpedoes" are right there, longer than the command pod (with props on the front, no less).

In addition, the claim is made by the inventor that the US Navy has no defense plan in place WRT small boat swarms, so his is the only solution. Wrong.

I can attest that is a blatant falsehood, and that our Navy does indeed train for exactly that sort of warfare. I don't think it is revealing any sensitive info to point out the fact that a certain well known, very-fast-boat manufacturer has an ongoing contract with the Navy conducting offshore exercises using 40-50' "attack" boats powered by twin or triple 250-300hp outboard engines. I've hung out many times with the guys running those boats, and they do not operate in any sort of "blacked out" manner. They use public and privately-owned marine facilities, and conduct operations in broad daylight within areas used by recreational offshore fisherman, so I am sure that the inventor is aware of them as well. These boats can easily run in excess of 70mph, and while they may be very high-dollar craft in the consumer market, they cost less than $500K apiece.

The one advantage his invention has over these conventional hulled boats (other than raw speed) is that this is a wave piercing [slashdot.org] design, which as stated ITFA is better for the health of those aboard. That said, I seriously doubt it has anywhere near the maneuverability of more conventional offshore craft such as those I mention above. The turning radius would have to be *extremely* large with that cat hull configuration, and even moreso at super cavitation speeds. And how large a sea state can it run in? Keeping that pod above water and waves at 200mph (or even 1/4 that speed) would be absolutely critical. Water being non-compressible, one good impact would likely render that platform unusable. So - it's very fast, but can't turn/maneuver for shit, and will primarily be useful only in areas where seas will remain relatively calm.

The inventor speaks glowingly about his $20-million-dollar-per solution becoming a multi-billion dollar industry. To me, knowing what I know about water craft, it seems to me as if he is selling the US Navy a marine version of TSA body scanners. Another Federal boondoggle...

After seeing firsthand what Juliet Marine built with $5 million, Kinsella said, “If you were taken around by a handler from Lockheed or Grumman or Northrop or any of them, and they told you, ‘We developed this on $150 million,’ you wouldn’t bat an eye.” He told the story of a meeting with Avalon and its fund investors. Someone asked Sancoff, “How did you get to be so capital efficient in your company?” Kinsella relays, “He leaned on the podium and said, ‘Because it was my money.’”

That just means the patent doesn't describe how this particular one works. It might describe part of how it works, it might describe a completely different approach, etc.

It also means that some part of the design isn't protected by that patent, which you would expect give the article also says "exactly how this is done is a trade secret" - and one thing can't be both a trade secret and a patented. I can however, combine a patented invention and a trade secret - just if the secret ever gets out I can't st